As shown in Japanese patent unexamined publication 2010-255316 (patent document 1), a conventional toilet for discharging waste by flushing the toilet with flush water is known. In the conventional toilet, a water spouting port is disposed in one location at an intermediate or rear position in the front-rear direction of the bowl portion in order to clean the comparatively easily dirtied rear surface portion of the toilet bowl portion interior, and the direction of the water spouting port is set so that after passing the rear surface portion of the bowl portion, the flush water spouted from the water spouting port swirls toward the front surface portion of the bowl portion.
Also, another toilet is known in which, as shown in Japanese patent unexamined publication 2000-265525 (patent document 2), a water outlet port is provided on either the left or right side within the front region of the toilet bowl portion interior, and the direction of spout water from this spout water port is directed rearward so that the rear surface portion of the bowl portion is cleaned.
Moreover, as shown in Japanese patent unexamined publication 2007-314975 (patent document 3), a flush toilet is also known in which a water spouting port is disposed at the front end part within the toilet bowl portion, and flush water is spouted toward the rear surface portion of the bowl portion.
Further, as shown in Japanese patent unexamined publication 2005-98003 (patent document 4), a flush toilet for discharging waste by flushing the toilet with flush water is known. In the toilet, the inner circumference of the rim portion formed on the top edge of the bowl portion of the flush toilet is formed in a shape which broadens vertically or toward the outside, such that flush water is spouted horizontally from rim spout ports formed on the rear side of the rim portion to form a swirling flow, and water is also spouted toward the discharge trap from a jet spout port disposed below and on the front end of the bowl portion to produce a siphon effect, thereby discharging waste.
Furthermore, as shown in Japanese patent unexamined publication 2007-169964 (patent document 5), a flush toilet is known. In the flush toilet, regarding the front and rear regions of the rim portion formed to spread outward at the top edge of the bowl portion, each forms the same arc shape with a fixed curvature radius, and a shelf return portion protruding inward on the toilet, which is a means for preventing the splashing of flush water to the outside of the toilet, is provided in the front region of the rim portion in the vicinity of the side portion formed in a straight line shape between the water spouting port at the rear side of the toilet and the front region of the rim portion.